The ability to acquire, process, analyze and display three-dimensional images of fixed and of living cells has become a common and critical need in modern cell biological research. Detailed analyses of the appearance, location, movements and turnover of selected molecules in the context of defined anatomical locations, cellular processes and structures provide essential information that cannot otherwise be obtained. Confocal laser- scanning microscopy provides this information in the form of three- dimensional image stacks and can simultaneously image multiple different fluorescent signals. No confocal microscope is currently available at our institution and the investigators represented by this proposal have so far depended on collaborations or increasingly limited access to the single locally-available confocal instrument in order to advance our research programs in areas that require three-dimensional imaging. The specific research projects outlined in this proposal address neuroanatomical development in C. elegans, expression and maturation of antibody production in B cells in culture and in germinal centers, B cell development in bone marrow, regulation and function of blood coagulation proteins on and in endothelial cells, and signaling' pathways leading to particle uptake in DT40 B cells. The investigators have immediate, ongoing needs for three-dimensional imaging at high resolution and in every case have prior experience with confocal microscopy. The requested system will be housed in the OMRF Core Imaging Facility and its use will be supervised by a well-trained Imaging Specialist in order to facilitate maintenance, training and access. The availability of this system will have a great impact on the quality and quantity of ongoing research at the OMRF.